import { base64, io } from "./deps.ts";

const stdinLines = io.readLines(Deno.stdin);

export function urlBase64Encode(data: ArrayBuffer) {
  return base64.encode(data)
    .replaceAll("+", "_")
    .replaceAll("/", "-")
    .replaceAll("=", "");
}

export function urlBase64Decode(data: string) {
  return base64.decode(
    data
      .replaceAll("_", "+")
      .replaceAll("-", "/"),
  );
}

export async function readline() {
  for await (const line of stdinLines) {
    if (line !== "") {
      return line;
    }
  }
  throw new Error("EOF");
}

type PromiseReturnType<T> = T extends () => Promise<infer R> ? R : never;
export async function retry<F extends () => Promise<unknown>>(
  f: F,
  times = 2,
): Promise<PromiseReturnType<F>> {
  let lastError;
  for (let i = 0; i < times; i++) {
    try {
      return await f() as PromiseReturnType<F>;
    } catch (e) {
      lastError = e;
    }
  }
  throw lastError;
}

const GLOBAL_CACHE: Record<string, { ts: number; value: unknown }> = {};
export function cache<F extends () => Promise<unknown>>(
  f: F,
  { key = f.name, expireIn = 3600 }: { key?: string; expireIn?: number } = {},
): () => Promise<PromiseReturnType<F>> {
  return async () => {
    const cached = GLOBAL_CACHE[key];
    if (cached && cached.ts + expireIn * 1000 > Date.now()) {
      return cached.value as PromiseReturnType<F>;
    }
    const value = await f();
    GLOBAL_CACHE[key] = {
      ts: Date.now(),
      value,
    };
    return value as PromiseReturnType<F>;
  };
}